Microbiology & sterility
Membrane filtration unit
A manifold with filter funnels connected to a vacuum source (or a peristaltic pump for closed canisters) that passes liquid samples through a 0.45 µm membrane so that microorganisms are retained and can be grown and counted.
- Pharmaceutical
- Biotech
- Water testing
- Food & beverage
- Medical devices
Follow your site SOP
This is a typical operating sequence for learning. Your instrument model and approved SOP take precedence.
STAGE 1
Preparation
- 1Sterilise funnels and forceps (autoclave) or use pre-sterilised single-use funnels.
- 2Disinfect the manifold and place it in the LAF, BSC or isolator.
- 3Check the vacuum is within the set range and the trap is empty.
- Never let liquid reach the vacuum pump; use a trap and hydrophobic filter.
STAGE 2
Filtration
- 1Place the membrane, grid side up, with sterile forceps; fit the funnel.
- 2Run a negative control (rinse fluid only) first.
- 3Mix the sample and pour the measured volume into the funnel; open the valve.
- 4Rinse the funnel walls and membrane with the validated volume of rinse fluid.
- 5Close the valve, remove the funnel and transfer the membrane to agar without trapping air bubbles.
- Do not let the membrane dry out under vacuum for long, as it stresses organisms.
STAGE 3
Afterwards
- 1Label and incubate plates.
- 2Disinfect the manifold, empty and decontaminate the trap.
- 3Sterilise reusable funnels before next use.
In LimsPulse · Calibration Management
Keep every Filtration unit in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.